Larch needle blight

• French disease name: Rouge du mélèze
• Other disease names: Hypodermella needle cast, larch needle cast
• Pathogen name: Hypodermella laricis Tub.
• Kingdom: Fungi
• Phylum: Ascomycota
• Class: Leotiomycetes
• Order: Rhytismatales
• Family: Rhytismataceae
• Partial list of synonyms:
  • Leptothyrella laricis Dearn

Distribution

• Canada

Damage, symptoms and biology

This disease does not kill large trees, but repeated infections can result in growth reduction.

This fungus generally kills the needles and secondary short shoots.

Other information

Needles affected by this disease suddenly turn yellow and then red-brown in the spring and early summer and infected needles are generally shed soon after they turn brown.

The rapid onset of disease symptoms could be confused with frost damage. Frost damage, however, tends to kill both needles and young stems, and no fruiting bodies are formed. Several rust fungi including Melampsora occidentalis, M. albertensis, and M. paradoxa Diet. & Holw. are also found on larch. These can be distinguished by their spore-producing fruiting structures (aecia).

Canadian Forest Service Publications

Larch needle blight

Information on host(s)

Main host(s)

• Subalpine larch
• Tamarack
• Western larch

Photos

Discoloured foliage of western larch affected by Hypodermella laricis

Bob Erickson

Hysterothecia of Hypodermella laricis on dead western larch needles

John Hopkins

Dead needles infected by Hypodermella laricis retained on western larch

Leo Unger